Epigenetics of regeneration in the aging brain PROJECT SUMMARY This project is designed to investigate the maturational decline in regenerative capability in the rat central nervous system. Our working hypothesis is that the intrinsic capacity for axon or dendritic regeneration results from an age-related alteration of epigenetic factors that regulate the organization of chromatin and accessibility of genes associated with neuronal survival and process outgrowth. This study will directly link altered transcriptome and acetylation and methylation enzymatic activity with axotomy and collateral axonal sprouting in vivo. Furthermore, we will provide the first evidence for the maturation-induced changes in the epigenetic landscape that lead to loss of neuronal plasticity in vivo. Our long term goal is to reverse age-induced alterations in the epigenetic landscape to promote neuronal survival and process outgrowth in the mature mammalian CNS. Reversal of maturation associated inhibition of regeneration will provide an important tool for promoting, regulating and directing a functionally relevant regeneration event in humans following traumatic brain injury, ischemia or neurodegenerative disease. The principle goals of this project are as follows: Aim 1: We will use an unbiased approach to compare the transcriptome and epigenomic profile in young regenerating vs aged non-regenerating hypothalamic neurons Aim 2: We will test how CNTF-induced JAK/STAT3 signaling triggers epigenetic and transcriptional events to mediate neuronal survival and axonal outgrowth. Aim 3: To determine how the PI3K-AKT pathway mediates CNTF-induced process outgrowth. In addition to applying a novel and highly relevant model system to the study of maturational changes in the SON neural and astrocyte epigenome, we propose to utilize new and innovative methods to address our specific objectives. We will take advantage of laser capture microdissection to directly assess the methylation and acetylation status of young versus mature and sprouting versus non sprouting neurons and astrocytes isolated from SON in situ. We will also interpret this data in conjunction with analysis of alterations in enzymatic activity of specific Dnmts, 5-mC hydroxylase TET activity, histone acetyltransferase, histone de-acetyltransferase and histone methyltransferase in isolated SON under similar experimental conditions.